Modeling analysis of negative effects of high frequency electrical stimulation on axonal behaviors

High frequency biphasic (HFB) electrical stimulation were commonly used in nerve block. This study constructed a double layer amphibian axonal model to explore the negative effects possibly caused by HFB electrical stimulation. The model was based on Frankenhaeuser-Huxley (FH) equations and McIntyre-Richardson-Grill (MRG) model geometry parameters. Sodium pump and ionic diffusion mechanisms for sodium, potassium, and chloride ions were included. HFB electrical stimulation of 10 kHz at 5 mA was applied for 5 s at half the axonal length. The action potentials recorded at node three fourth of axonal length exhibited larger delays, smaller amplitudes and more positive pre-occurring resting potentials than normal ones. Changes of intracellular ionic concentrations were observed and considered as one main mechanism underlying the axonal behavior changes induced by HFB electrical stimulation. This study provides useful information about mechanism of nerve injury caused by HFB electrical blocking stimulation.